A comparative study and dose evaluation of photon beam for water phantom : 2D-array and treatment planning system in small field sizes

الملخص EN

This study assessed the clinical usefulness of the 2D-Array Seven29 ,which may compensate for the of the water phantom, by comparing the radiological doses between the two depending on five field sizes.

The experimental equipment used was a linear accelerator for medical use, treatment planning system (TPS) , water phantom, 2D-Array, solid phantoms,( Semiflex , Pinpoint) types ion chamber and electrometer.

The field size was 10 x 10 cm2 and the radiation energies of the photon beam were 6 MV and 15 MV, The field size involved (1×1, 2×2, 3×3, 4×4, 5×5,) for each energy.

The relative deviation ratio of the TPS to both chamber in water phantom and TPS to 2darray in the solid phantom was calculated.

The measured doses in standard phantom were less than the TPS values for small field dimensions for fields less than 3×3 cm2, The measured data by 2D-Array data for fields 2×2 and 3×3cm2 this difference within ±2% is due to good accuracy of measurement planning system for field size 1×1cm2.

The measured in standard phantom were less than the TPS values for small field dimensions and the measured data by 2D-Array for 6 MV shows mild differences between the TPS and the experimental data.

Small difference existed between the TPS and the experimental data using 2D-Array for 15 MV the results were the same for TPS and measured data, at only field dimension of 1×1cm2.

Measured data was increased as field area enlarged from 2×2 to 5×5cm2 by constant value of 4%.